I have a 360 in my wife's duster that has an RPM Air Gap intake, and until last week had a Holley 4160 600cfm carb and have been using AR Engineering brackets which were perfect......until I pulled the Holley 4160 off and put on a Street Demon 625.

The biggest problem I'm having is with the cruise control cable. if I try and attach it to the throttle cable pin, it's in too much of a bind and won't retract when the throttle is applied. So my first solution was to put it on the pin in the attached picture. This will work, but limits me to only being able to open the butterfly's 75% before the cable bottoms out, or if I adjust it so that I can fully open the butterfly's, the throttle won't be able to return to closed.

I've scoured most of the forums looking at as many pictures as I can find, but haven't found any that shed any light on how I can attach the cruise control cable.

I suspect it would work, if the throttle cable bracket were at the same level as the carburetor lever and the throttle and cruise control cables were mounted side by side, allowing them to travel at the same ratio. From the picture, it can also been observed that the throttle cable interferes slightly with the linkage on the carburetor, if it was higher and on the same plane, this wouldn't be the case.

anyone want to throw an idea out there?


(side note, the Street Demon is leaps and bounds better than the 600CFM Holley 4160 it replaced and I'm extremely happy with it so far).

fabricate a bracket to get them on the same plane. Without seeing the entire setup it's hard to comment on any other solution
EDIT:
If the lower cable is the throttle and the upper is the cruise, doesn't appear as though it would be that hard to tack weld a tube to the side of the bracket that clamps the throttle cable.
If said tube had enough wall thickness a couple of small set screws to position the cable and attach it to the opposite side of the throttle arm

Where is your lost motion link?

I think you should back up and start over?

the geometry works out a lot better if you use a holley carb throttle lever extension and a Chrysler throttle stud. I think you'll need to drill a hole to attach the lost motion link.

Is this a lost motion link? (This is what appears to be where the cruise control cable would attached on a Thermoquad.

Yep, check the service manual for the adjustment. IIRC, 1/16" clearance required. I think the suggested bracket has the mounting hole? Can't recall anymore

well....it was a great idea....but due to the shape of the Holley adapter bracket, the orientation from the throttle stud to the hole for the roll pin that the lost motion link attaches do changes too much.

Well, that just sucks. I think if there was a way to move the LM link pivot forward (front of car) and up it'd still work? Short of adding material to the bracket and drilling a new hole I don't see a way forward. There are ~ 6 -8 different LM links available but I don't think any of them will fix this.

I'd looked at the pics before and wasn't sure how to attach the LM link to the Street Demon so was curious about how and if it'd work. My preliminary look see led me to favor the AVS2 when and if the time came for a another carburetor. Dang, really liked what I was hearing about the SD. But my luxo barges are keeping the CC's.

adding material and re-shaping the holley bracket is exactly what I'm going to do. I don't really want this trail to create any negative marks against the Street Demon because in reality, when I looked at my Edelbrock 750 and Edelbrock 800 Thunder Series, this exact same issue will be come across with them when trying to get the cruise control to function. I'm going to have to do this again with the Edelbrock 750 on the 440 in the Ramcharger.

I really wonder what the cruise control lost motion link looks like on pre-1971 mopars that didn't have Thermoquad's.


edit - looks like it's a littel more straight forward with the Edelbrock carb's than I had suspected. https://www.forcbodiesonly.com/mopar-forum/threads/to-cruise-or-not-to-cruise.51043/

Pretty sure that "lost motion' link was all the same . . . I have had on AVS carbs from my C bodies . . . same piece on TQ . . .

Mark

I used to think so too. Somebody on FCBO posted a pic of the various ones, slight differences is all I saw. I can only presume the various carburetor brands and barrel counts differ a bit?

Anyway, I'd like to see how he gets this done. 2¢

This is how I'm going to make it work. I'll get this welded up, sand it down smooth, paint it and slap it on.

It's ugly, but as long as I drill the hole correctly, the geometry will be the exact same orientation as the Thermoquad I'm using for reference.

Done.....I'm so much happier with the car now...it'll burn them down effortlessly. This is the way!

I'm going to return the carb stud to Summit. It's bad advertising on Holley's part to market it as "Chrysler Throttle & Cruise" when in face the cruise never attaches to it.

Now that I've worked the linkage I understand what the lost motion link does. Since the cruise cable only has about half the motion of the throttle cable, the link allows the cruise cable to stay behind without impeding the throttle cables pull. Essentially it stops when the throttle cable just gets into the secondaries.

Holley should really design their linkages to be able to accept the lost motion link the same way Edelbrock does. I ended up just positioning the hole for the lost motion link's roll pin orientated the exact same distance and direction as it is on a Thermoquad.

But Holley's are for race cars and race cars do not use cruise control.

Or so they think.

Congratulations and nice work!

I would have first got the throttle cable bracket parallel to the carb & linkage & then worked from there.